Electron gun alignment method and device therefor

ABSTRACT

AN ALIGNING JIG AND METHOD OF OPERATION TO PRECISELY ALIGN THE G1 AND G2 ELECTRODE APERTURES OF AN ELECTRON GUN IS DISCLOSED. A ALIGNING MANDREL IS POSITIONED IN ONE APERTURE AND ADJACENT THE OTHER AND ROTATED TO VIEW MISALIGNMENT. THE SUPPORTING CYLINDER IS THEN MANUALLY DISTORTED TO PRODUCE APERTURE ALIGNMENT.

June 1, 1971 QESS 3,581,357

ELECTRON GUN ALIGNMENT METHOD AND DEVICE THEREFOR Original Filed Jan. 2. 1968 2 Sheets-Sheet l fEafz/az a 0651, av

F. G. OESS June 1, 1971 ELECTRON GUN ALIGNMENT METHOD AND DEVICE THEREFOR Original Filed Jan. 2. 1968 2 Sheets-Sheet 7'.

United States Patent 3,581,357 ELECTRON GUN ALIGNMENT METHOD AND DEVICE THEREFOR Frederick G. Oess, Oceanside, Calif., assignor to Hughes Aircraft Company, Culver City, Calif.

Original application Jan. 2, 1968, Ser. No. 695,078, now Patent No. 3,510,926, dated May 12, 1970. Divided and this application Oct. 8, 1969, Ser. No. 871,198

Int. Cl. H01j 9/18, 9/36 US. Cl. 29-2516 4 Claims ABSTRACT OF THE DISCLOSURE An aligning jig and method of operation to precisely align the G1 and G2 electrode apertures of an electron gun is disclosed. An aligning mandrel is positioned in one aperture and adjacent the other and rotated to view misalignment. The supporting cylinder is then manually distorted to produce aperture alignment.

This is a division of application Ser. No. 695,078, filed Jan. 2, 1968 now Pat. No. 3,510,926. The invention relates to a method of aligning electrodes forming part of an electron gun and a device for accomplishing said alignment.

Structurally a typical electron gun comprises an annular cylinder having a cathode at one end thereof, a G1 electrode mounted forwardly of the cathode and a G2 electrode positioned forwardly in the G1 electrode. Both the G1 and G2 electrodes are provided with central apertures aligned with the electron emitting face of the cathode, the apertures providing openings to permit passage of the created electron beam. The operating efficiency of any electron gun is importantly aifected by the proper alignment of the G1 and G2 apertures. The more precise this alignment the better the operating characteristics of the gun.

The present invention provides a method of obtaining precise alignment of the apertures of the G1 and G2 electrodes. Though applicable to electron guns of various configurations, the disclosed method is particularly adapted to provide precise alignment for that type of electron gun structure as shown in my co-pending application filed on instant date herewith and entitled Electron Gun Electrode Mounting Arrangement and Method of Fabrication.

Accordingly, it is the primary object of the present invention to provide a method of obtaining precise alignment of the apertures of the G1 and G2 electrodes in a typical electron gun, and at a point in the assembly operation after mounting of the G1 and G2 electrodes to a supporting cylinder.

It is the further object of the invention to provide a method of determining, if desired, the degree of misalignment existent in a given electron gun structure between the beam assing apertures of the G1 and G2 electrodes.

It is yet another object of the invention to provide a novel aligning jig not only adapted to determining the degree of misalignment between G1 and G2 apertures but providing an operative mode to realign, with a high degree of preciseness, misaligned G1 and G2 apertures in a partially fabricated electron gun.

These and other objects and features of the invention will become apparent in the course of the following description and from the examination of the related drawings, wherein:

FIG. 1 is a fragmentary illustration of a coining operation adapted to provide precise sizing of the beam passing aperture in a G2 electrode;

FIG. 2 is a central vertical sectional view, partially fragmentary, of a jig arrangement adapted to perform the method herein disclosed;

FIG. 3 is a visual representation of the device appearance to an operator of an electron gun having misaligned G1 and G2 apertures;

FIG. 4 is a graphic representation of the device appearance to the operator of an electron gun having aligned G1 and G2 apertures; and

FIG. 5 is a fragmentary sectional view taken along line 55 of FIG. 2 illustrating the structure of FIG. 2 used to provide aperture alignment for electron guns wherein the apertures were misaligned upon original fabrication.

Describing the invention in detail in directing attention initially to FIG. 2, an aligning jig indicated generally at 10 is provided having a base 12 with an upstanding support mandrel 14. The support mandrel 14 is telescopically received in the cylinder 16, as shown at the lower portion of FIG. 2. The electron gun support cylinder 16 with the G1 electrode 18 and the G2 electrode 20 assembled thereto is positioned over the supporting mandrel 14 so that the cavity of the G2 electrode 20 telescopically receives the supporting mandrel 14. A clearance of approximately one to two-thousandths of an inch may be provided between an external surface of the supporting mandrel 14 and the internal surface of the cavity of the G2 electrode 20. An adjusment sleeve 22 is positioned to surround the supporting cylinder 16 to provide backup reinforcement to the cylinder 16 and to bring the adjusting screws 24, 24 into alignment with dimples 26, 26 formed in the peripheral wall of the cylinder 16. As noted in the referenced patent application the dimples 26 provide points of Weld connection between the cylinder wall 16 and the surface of the G2 electrode 20.

The support mandrel 14 is centrally apertured as at 28, said aperture having an alignment bearing 30 at its lower aspect. Aligning mandrel 32 is carried in the cavity 28 and supported by the bearing 30 for precise alignment Within base 12. The upper tip of the mandrel 32 is received within the G2 aperture 34 so that the axial edge of the mandrel 32 is positioned immediately below the G1 aperture 36.

It will be understood that precise sizing of the G2 aperture 34 is an important facet in obtaining the proper alignment of the apertures 36 and 34 as hereinafter will be described. Accordingly, and as a preliminary step prior to the utilization of the aligning device 10, the G2 electrode 20 is positioned in a sizing die indicated generally as 40 in FIG. 1, said die comprising a base member 42 and a sizing member 44 and sizing pin 46. The sizing pin 46 is provided with a diameter identical with the alignment mandrel 32. The dotted line 48 in FIG. 1 illustrates the configuration of aperture 34 prior to the sizing and coining operation. The coining element 44 is provided with an angled die segment 50 which annularly surrounds the opening 52 formed in element 44. In a conventional coining operation, the die element 44 is impacted against the wall 52 of the G2 electrode 20 whereby the angled die segment 50 of die element 44 induces the material of wall 52 to flow radially inwardly and to tightly conform to the diameter of sizing pin 46. Thus, the aperture 34 is precisely sized to the diameter of the alignment mandrel 32 prior to the aligning operation utilizing device 10 of FIG. 2.

Returning to FIG. 2, it will be understood that the tip 54 of the mandrel 32 is provided with visible markings 56 which may be circular grinding marks formed at the top end which provide concentric indicia about the exact center 58 of the mandrel tip 54. If desired, other marking indicia may be utilized to visibly define the exact center of the mandrel tip.

An operators microscope 60 which is used to magnify and view the tip 54 of the mandrel 32 is positioned to view the openings of apertures 34 and 36 and the visible segment of the tip 54. The mandrel 32 is provided with a rotating knob 62 which may be turned by the operator to induce rotation of the mandrel 32 and its tip 54. The operator, concurrently with rotation of the knob 62, views the apertures 34 and 36 via the microscope 60 and if the apertures 34 and 36 are misaligned the field of view appears as shown in FIG. 3. As shown in FIG. 3, it is obvious that the center of the opening 34 in the G2 electrode 20 is misaligned with the opening 36 of the G1 electrode 18. To correct misalignment, three adjusting screws arranged in 120 degree angular spacing (FIG. 5) may be alternately and selectively rotated to selectively apply distorting pressure to the respective adjusting screws 24. The distortions induced by the adjusting screws 20 change the position of the central aperture 34 of the G2 electrode 20 in relation to the central longitudinal axis of the carrying cylinder 16. This change results from small or minor distortions in the surface of the cylinder 16, as well as repositioning of the G2 electrode 20 internally in the cylinder. The operation is successively re peated by the operator with continued visual examination of the appearance of the mandrel tip 54 via the microscope 60 with concurrent rotation of the knob 62 until such time as the center of the tip appears to be centrally aligned with the aperture 36 of the G1 electrode 18. The appearance upon a proper alignment of the tip 54 is shown in FIG. 4. Once alignment is obtained the operator retracts adjusting screws 24 to relieve pressure induced thereby, again checks the alignment of the openings 34 and 36 by mandrel rotation and if the center condition still obtains no further repetitive centering operations are required.

If misalignment returns upon loosening of the adjusting screws 24, the above described operations are repeated until exact aperture alignment is obtained. After alignment has been properly obtained, adjustment sleeve 22 may be removed, the electron gun supporting cylinder 16 can be removed from mandrel 14 and thereafter sub ject to further fabrication.

As earlier noted, a major factor in the proper operation of an electron gun is the precise alignment of the beam passing apertures in the G1 and G2 electrodes. The present invention provides a mode for accurately sizing the G2 aperture in a facile and economic manner. Additionally, the novel aligning jig provides an easy and simple mode of determining both the degree and direction of misalignment between the G1 and G2 apertures of partially manufactured electron guns. In addition to providing an easy check for possible misalignment, the device offers a mode of simple and efiicient mechanical distortion of each gun to return misaligned apertures to proper alignment. Scrap loss during electron gun production is thereby minimized.

The invention as shown is by Ways of illustration and not limitation and may be modified in many aspects, all within the scope and the spirit of the invention.

What is claimed is:

1. In a method of aligning the apertures of a plurality of electrodes in an electron gun wherein the gun comprises a supporting cylinder and first and second electrodes carried within the cylinder, the steps of telescopically positioning a rotatable aligning mandrel within the aperture of one electrode so that the tip of the mandrel is visible through the aperture in the other electrode, viewing the tip through the other electrode aperture, said tip having indicia thereon to indicate the center thereof, rotating the mandrel and concurrently viewing the tip to determine the location of the mandrel tip in relation to the center of the other electrode aperture, and mechanically distorting the cylinder to precisely align the center of the mandrel tip with the center of the other electrode aperture.

2. A method of aligning the apertures of a pair of electrodes according to claim 1, wherein said distorting is selectively undertaken annularly around the cylinder.

3. A method of aligning the apertures of a pair of electrodes in an electron gun according to claim 2, and including initially coining said one electrode to accurately size the aperture therein to the diameter of the mandrel.

4. A method of aligning the apertures of a pair of electrodes in an electron gun according to claim 3, wherein viewing the mandrel tip through the other electrode is accomplished via a magnifying device.

References Cited UNITED STATES PATENTS 2,305,458 12/1942 Ruska et al. 3 1623X 3,151,381 10/1964 Hedel 2925.l9 3,289,268 12/1966 Bernardis 2925.19

JOHN F. CAMPBELL, Primary Examiner R. B. LAZARUS, Assistant Examiner US. Cl. 316-23, 29 

